Design for Compact Camera

ABSTRACT

Infrared cameras can include an infrared sensor and an infrared lens assembly defining an optical axis. A camera can include an inner gear engaging the infrared lens assembly and a focus ring that engages the inner gear. The inner gear can engage the focus ring and the infrared lens assembly such that rotation of the focus ring about its central axis can cause the rotation of the infrared lens assembly about its optical axis, which may be offset from the central axis of the focus ring. The camera can include a sensor can threadably engaging the infrared lens assembly and fixed relative to the infrared sensor such that rotation of the infrared lens assembly causes the infrared lens assembly to move relative to the infrared sensor. The sensor can support other components such as a visible light lens assembly or a laser within a perimeter of the focus ring.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 15/057,807, filed Mar. 1, 2016 and titled “DESIGNFOR COMPACT CAMERA,” the entire content of which is incorporated hereinby reference.

BACKGROUND

Thermal imaging cameras are used in a variety of situations. Forexample, thermal imaging cameras are often used during maintenanceinspections to thermally inspect equipment. Example equipment mayinclude rotating machinery, electrical panels, or rows of circuitbreakers, among other types of equipment. Thermal inspections can detectequipment hot spots such as overheating machinery or electricalcomponents, helping to ensure timely repair or replacement of theoverheating equipment before a more significant problem develops.

Traditional manual focus cameras use a focus ring concentric with theinfrared imaging axis of the camera. Typically, users prefer a largediameter focus ring to allow ease of focus, and so that the user can seethe edges of the focus ring around the edges of the camera when viewingthe back of the camera. The combination of a concentric and large focusring enlarges the physical size of the camera. However, a large cameraincreases weight and can make the camera more difficult to use.Additionally, an infrared imaging axis concentric with the focus ringleaves little room for additional components to be positioned proximatethe infrared imaging axis. Accordingly, additional components such asvisible light cameras, laser pointers, torches, and the like aretypically positioned a considerable distance from the infrared imagingaxis, contributing to parallax errors.

SUMMARY

Aspects of the present disclosure are directed toward cameras andassembly methods therefor. Cameras can include an infrared sensorconfigured to receive infrared radiation from a target scene andgenerate infrared image data of the target scene. A camera can furtherinclude an infrared lens assembly comprising at least one lens definingan optical axis. The infrared lens assembly can be configured to focusinfrared radiation onto the infrared sensor. A focus ring can be used toadjust the position of the infrared lens assembly relative to theinfrared sensor, thereby adjusting the focus of the camera.

In some examples, the focus ring substantially surrounds the infraredlens assembly. The focus ring can be configured such that rotation ofthe focus ring about its central axis can cause the infrared lensassembly to move relative to the infrared sensor. For example, in someembodiments, the camera includes an inner gear that includes an outersurface that engages an inner surface of the focus ring and an innersurface that engages and substantially surrounds a portion of theinfrared lens assembly. The inner gear can be configured such that therelative engagement between the focus ring, the inner gear, and the lensassembly causes the infrared lens assembly to rotate about its opticalaxis when the focus ring is rotated about its central axis. In someembodiments, the central axis of the focus ring is offset from theoptical axis of the at least one lens in the infrared lens assembly.

According to some embodiments, a camera can include a sensor canconfigured to support the infrared lens assembly. For example, theinfrared lens assembly may be threadably engaged with the sensor can. Insome such examples, a spring or other element can apply pressure betweenthe infrared lens assembly and the sensor can to rigidly hold theinfrared lens assembly steady relative to the sensor can. Because of thethreaded engagement, rotating the focus ring relative to the sensor cancause the infrared lens assembly to similarly rotate within the sensorcan and translate relative thereto because of the threaded engagement.The sensor can may be fixed relative to the infrared sensor so thattranslation of the infrared lens assembly relative to the sensor cansimilarly causes translation of the infrared lens assembly relative tothe infrared sensor.

Exemplary cameras can further include a visible light sensor configuredto receive visible light radiation from a target scene and generatevisible light image data representative of the target scene and avisible light lens assembly configured to focus visible light radiationonto a visible light sensor. In some examples, the visible light lensassembly is supported by the sensor can. The camera can additionally oralternatively include a laser, which can be supported by the sensor can.In some embodiments, the visible light lens assembly and/or the lasercan be supported by the sensor can and positioned within the perimeterof the focus ring.

In some embodiments, a camera can include a sensor configured todetermine the focal position of the infrared lens assembly relative tothe infrared sensor. In some such embodiments, the camera can include adetector fixed relative to the infrared sensor and a plunger adapted tomove as the infrared lens assembly moves. The sensor can be capable ofsensing the relative distance to the plunger and relative movement ofthe plunger toward and away from the detector.

Assembly methods for some such cameras can include threadably engagingthe infrared lens assembly onto the sensor can and inserting theinfrared lens assembly into a housing from a back side of the housing.An inner gear can be attached to the infrared lens assembly via a frontside of the housing and a focus ring can be positioned on the front sideof the housing such that an inner surface of the focus ring engages anouter surface of the inner gear. In some examples, when assembled assuch, rotation of the focus ring can likewise cause rotation of theinner gear and the infrared lens assembly relative to the sensor can,causing the infrared lens assembly to translate relative to the sensorcan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective front view of an example thermal imaging camera.

FIG. 2 is a perspective back view of the example thermal imaging cameraof FIG. 1.

FIG. 3 is a functional block diagram illustrating example components ofthe thermal imaging camera of FIGS. 1 and 2.

FIG. 4 is a front view of a thermal imaging camera such as that shown inFIG. 1.

FIG. 5 is a front view of a thermal imaging camera such as that of FIG.4 with the faceplate removed.

FIG. 6 is an exploded view of portions of an exemplary thermal imagingcamera according to some embodiments.

FIG. 7 is a back view of an exemplary focus ring and inner gear.

FIG. 8 is an exploded view showing an exemplary configuration between aninner gear and an infrared lens assembly.

FIG. 9 is a cross-sectional view of portions of an exemplary thermalimaging camera taken along line 9-9 in FIG. 5.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing various embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of ordinary skill inthe field of the invention. Those skilled in the art will recognize thatmany of the noted examples have a variety of suitable alternatives.

A thermal imaging camera may be used to detect heat patterns across ascene, including an object or objects, under observation. The thermalimaging camera may detect infrared radiation given off by the scene andconvert the infrared radiation into an infrared image indicative of theheat patterns. In some embodiments, the thermal imaging camera may alsocapture visible light from the scene and convert the visible light intoa visible light image. Depending on the configuration of the thermalimaging camera, the camera may include infrared optics to focus theinfrared radiation on an infrared sensor and visible light optics tofocus the visible light on a visible light sensor.

Various embodiments provide methods and systems for producing thermalimages with reduced noise using averaging techniques. To further improveimage quality and eliminate problems that may arise from averaging (e.g.blurring, ghosting, etc.), an image alignment process is performed onthe thermal images prior to averaging.

FIGS. 1 and 2 show front and back perspective views, respectively of anexample thermal imaging camera 100, which includes a housing 102, aninfrared lens assembly 104, a visible light lens assembly 106, a display108, a laser 110, and a trigger control 112. Housing 102 houses thevarious components of thermal imaging camera 100. The bottom portion ofthermal imaging camera 100 includes a carrying handle 118 for holdingand operating the camera via one hand. Infrared lens assembly 104receives infrared radiation from a scene and focuses the radiation on aninfrared sensor for generating an infrared image of a scene. Visiblelight lens assembly 106 receives visible light from a scene and focusesthe visible light on a visible light sensor for generating a visiblelight image of the same scene. Thermal imaging camera 100 captures thevisible light image and/or the infrared image in response to depressingtrigger control 112. In addition, thermal imaging camera 100 controlsdisplay 108 to display the infrared image and the visible light imagegenerated by the camera, e.g., to help an operator thermally inspect ascene. Thermal imaging camera 100 may also include a focus mechanismcoupled to infrared lens assembly 104 that is configured to move atleast one lens of the infrared lens assembly so as to adjust the focusof an infrared image generated by the thermal imaging camera.Additionally or alternatively, the focus mechanism may move the FPArelative to one or more lenses of the infrared lens assembly.

In operation, thermal imaging camera 100 detects heat patterns in ascene by receiving energy emitted in the infrared-wavelength spectrumfrom the scene and processing the infrared energy to generate a thermalimage. Thermal imaging camera 100 may also generate a visible lightimage of the same scene by receiving energy in the visiblelight-wavelength spectrum and processing the visible light energy togenerate a visible light image. As described in greater detail below,thermal imaging camera 100 may include an infrared camera module that isconfigured to capture an infrared image of the scene and a visible lightcamera module that is configured to capture a visible light image of thesame scene. The infrared camera module may receive infrared radiationprojected through infrared lens assembly 104 and generate therefrominfrared image data. The visible light camera module may receive lightprojected through visible light lens assembly 106 and generate therefromvisible light data.

In some examples, thermal imaging camera 100 collects or captures theinfrared energy and visible light energy substantially simultaneously(e.g., at the same time) so that the visible light image and theinfrared image generated by the camera are of the same scene atsubstantially the same time. In these examples, the infrared imagegenerated by thermal imaging camera 100 is indicative of localizedtemperatures within the scene at a particular period of time while thevisible light image generated by the camera is indicative of the samescene at the same period of time. In other examples, thermal imagingcamera may capture infrared energy and visible light energy from a sceneat different periods of time.

Visible light lens assembly 106 includes at least one lens that focusesvisible light energy on a visible light sensor for generating a visiblelight image. Visible light lens assembly 106 defines a visible lightoptical axis which passes through the center of curvature of the atleast one lens of the assembly. Visible light energy projects through afront of the lens and focuses on an opposite side of the lens. Visiblelight lens assembly 106 can include a single lens or a plurality oflenses (e.g., two, three, or more lenses) arranged in series. Inaddition, visible light lens assembly 106 can have a fixed focus or caninclude a focus adjustment mechanism for changing the focus of thevisible light optics. In examples in which visible light lens assembly106 includes a focus adjustment mechanism, the focus adjustmentmechanism may be a manual adjustment mechanism or an automaticadjustment mechanism.

Infrared lens assembly 104 also includes at least one lens that focusesinfrared energy on an infrared sensor for generating a thermal image.Infrared lens assembly 104 defines an infrared optical axis which passesthrough the center of curvature of lens of the assembly. Duringoperation, infrared energy is directed through the front of the lens andfocused on an opposite side of the lens. Infrared lens assembly 104 caninclude a single lens or a plurality of lenses (e.g., two, three, ormore lenses), which may be arranged in series. In some examples, theinfrared lens assembly 104 may include lenses having diffractive orreflective properties or elements. Additional optical components such asmirrors (e.g., Fresnel mirrors) and the like may be included within orotherwise proximate to the infrared lens assembly 104.

As briefly described above, thermal imaging camera 100 includes a focusmechanism for adjusting the focus of an infrared image captured by thecamera. In the example shown in FIGS. 1 and 2, thermal imaging camera100 includes focus ring 114. Focus ring 114 is operatively coupled(e.g., mechanically and/or electrically coupled) to at least one lens ofinfrared lens assembly 104 and configured to move one or both of the FPAand the at least one lens to various focus positions so as to focus theinfrared image captured by thermal imaging camera 100. Focus ring 114may be manually rotated about at least a portion of housing 102 so as tomove the at least one lens to which the focus ring is operativelycoupled. In some examples, focus ring 114 is also operatively coupled todisplay 108 such that rotation of focus ring 114 causes at least aportion of a visible light image and at least a portion of an infraredimage concurrently displayed on display 108 to move relative to oneanother. In different examples, thermal imaging camera 100 may include amanual focus adjustment mechanism that is implemented in a configurationother than focus ring 114, or may, in other embodiments, simply maintaina fixed focus.

In some examples, thermal imaging camera 100 may include anautomatically adjusting focus mechanism in addition to or in lieu of amanually adjusting focus mechanism. An automatically adjusting focusmechanism may be operatively coupled to at least one lens of infraredlens assembly 104 and configured to automatically move the at least onelens to various focus positions, e.g., in response to instructions fromthermal imaging camera 100. In one application of such an example,thermal imaging camera 100 may use laser 110 to electronically measure adistance between an object in a target scene and the camera, referred toas the distance-to-target. Thermal imaging camera 100 may then controlthe automatically adjusting focus mechanism to move the at least onelens of infrared lens assembly 104 to a focus position that correspondsto the distance-to-target data determined by thermal imaging camera 100.The focus position may correspond to the distance-to-target data in thatthe focus position may be configured to place the object in the targetscene at the determined distance in focus. In some examples, the focusposition set by the automatically adjusting focus mechanism may bemanually overridden by an operator, e.g., by rotating focus ring 114.

During operation of thermal imaging camera 100, an operator may wish toview a thermal image of a scene and/or a visible light image of the samescene generated by the camera. For this reason, thermal imaging camera100 may include a display. In the examples of FIGS. 1 and 2, thermalimaging camera 100 includes display 108, which is located on the back ofhousing 102 opposite infrared lens assembly 104 and visible light lensassembly 106. Display 108 may be configured to display a visible lightimage, an infrared image, and/or a combined image that includes asimultaneous display of the visible light image and the infrared image.In different examples, display 108 may be remote (e.g., separate) frominfrared lens assembly 104 and visible light lens assembly 106 ofthermal imaging camera 100, or display 108 may be in a different spatialarrangement relative to infrared lens assembly 104 and/or visible lightlens assembly 106. Therefore, although display 108 is shown behindinfrared lens assembly 104 and visible light lens assembly 106 in FIG.2, other locations for display 108 are possible.

Thermal imaging camera 100 can include a variety of user input media forcontrolling the operation of the camera and adjusting different settingsof the camera. Example control functions may include adjusting the focusof the infrared and/or visible light optics, opening/closing a shutter,capturing an infrared and/or visible light image, or the like. In theexample of FIGS. 1 and 2, thermal imaging camera 100 includes adepressible trigger control 112 for capturing an infrared and visiblelight image, and buttons 116, which form part of the user interface, forcontrolling other aspects of the operation of the camera. A differentnumber or arrangement of user input media are possible, and it should beappreciated that the disclosure is not limited in this respect. Forexample, thermal imaging camera 100 may include a touch screen display108 which receives user input by depressing different portions of thescreen.

FIG. 3 is a functional block diagram illustrating components of anexample of thermal imaging camera 100. Thermal imaging camera 100includes an IR camera module 200, front end circuitry 202. The IR cameramodule 200 and front end circuitry 202 are sometimes referred to incombination as front end stage or front end components 204 of theinfrared camera 100. Thermal imaging camera 100 may also include avisible light camera module 206, a display 108, a user interface 208,and an output/control device 210.

Infrared camera module 200 may be configured to receive infrared energyemitted by a target scene and to focus the infrared energy on aninfrared sensor for generation of infrared energy data, e.g., that canbe displayed in the form of an infrared image on display 108 and/orstored in memory. Infrared camera module 200 can include any suitablecomponents for performing the functions attributed to the module herein.In the example of FIG. 3, infrared camera module 200 is illustrated asincluding infrared lens assembly 104 and infrared sensor 220. Asdescribed above with respect to FIGS. 1 and 2, infrared lens assembly104 includes at least one lens that takes infrared energy emitted by atarget scene and focuses the infrared energy on infrared sensor 220.Infrared sensor 220 responds to the focused infrared energy bygenerating an electrical signal that can be converted and displayed asan infrared image on display 108.

Infrared sensor 220 may include one or more focal plane arrays (FPA)that generate electrical signals in response to infrared energy receivedthrough infrared lens assembly 104. Each FPA can include a plurality ofinfrared sensor elements including, e.g., bolometers, photon detectors,or other suitable infrared sensor elements. In operation, each sensorelement, which may each be referred to as a sensor pixel, may change anelectrical characteristic (e.g., voltage or resistance) in response toabsorbing infrared energy received from a target scene. In turn, thechange in electrical characteristic can provide an electrical signalthat can be received by a processor 222 and processed into an infraredimage displayed on display 108.

For instance, in examples in which infrared sensor 220 includes aplurality of bolometers, each bolometer may absorb infrared energyfocused through infrared lens assembly 104 and increase in temperaturein response to the absorbed energy. The electrical resistance of eachbolometer may change as the temperature of the bolometer changes. Witheach detector element functioning as a sensor pixel, a two-dimensionalimage or picture representation of the infrared radiation can be furthergenerated by translating the changes in resistance of each detectorelement into a time-multiplexed electrical signal that can be processedfor visualization on a display or storage in memory (e.g., of acomputer). Processor 222 may measure the change in resistance of eachbolometer by applying a current (or voltage) to each bolometer andmeasure the resulting voltage (or current) across the bolometer. Basedon these data, processor 222 can determine the amount of infrared energyemitted by different portions of a target scene and control display 108to display a thermal image of the target scene.

Independent of the specific type of infrared sensor elements included inthe FPA of infrared sensor 220, the FPA array can define any suitablesize and shape. In some examples, infrared sensor 220 includes aplurality of infrared sensor elements arranged in a grid pattern suchas, e.g., an array of sensor elements arranged in vertical columns andhorizontal rows. In various examples, infrared sensor 220 may include anarray of vertical columns by horizontal rows of, e.g., 16×16, 50×50,160×120, 120×160, or 650×480. In other examples, infrared sensor 220 mayinclude a smaller number of vertical columns and horizontal rows (e.g.,1×1), a larger number vertical columns and horizontal rows (e.g.,1000×1000), or a different ratio of columns to rows.

In certain embodiments a Read Out Integrated Circuit (ROIC) isincorporated on the IR sensor 220. The ROIC is used to output signalscorresponding to each of the sensor pixels. Such ROIC is commonlyfabricated as an integrated circuit on a silicon substrate. Theplurality of detector elements may be fabricated on top of the ROIC,wherein their combination provides for the IR sensor 220. In someembodiments, the ROIC can include components discussed elsewhere in thisdisclosure (e.g. an analog-to-digital converter (ADC)) incorporateddirectly onto the FPA circuitry. Such integration of the ROIC, or otherfurther levels of integration not explicitly discussed, should beconsidered within the scope of this disclosure.

As described above, the IR sensor 220 generates a series of electricalsignals corresponding to the infrared radiation received by eachinfrared detector element to represent a thermal image. A “frame” ofthermal image data is generated when the voltage signal from eachinfrared detector element is obtained by scanning all of the rows thatmake up the IR sensor 220. Again, in certain embodiments involvingbolometers as the infrared detector elements, such scanning is done byswitching a corresponding detector element into the system circuit andapplying a bias voltage across such switched-in element. Successiveframes of thermal image data are generated by repeatedly scanning therows of the IR sensor 220, with such frames being produced at a ratesufficient to generate a video representation (e.g. 30 Hz, or 60 Hz) ofthe thermal image data.

The front end circuitry 202 includes circuitry for interfacing with andcontrolling the IR camera module 200. In addition, the front endcircuitry 202 initially processes and transmits collected infrared imagedata to a processor 222 via a connection therebetween. Morespecifically, the signals generated by the IR sensor 220 are initiallyconditioned by the front end circuitry 202 of the thermal imaging camera100. In certain embodiments, as shown, the front end circuitry 202includes a bias generator 224 and a pre-amp/integrator 226. In additionto providing the detector bias, the bias generator 224 can optionallyadd or subtract an average bias current from the total current generatedfor each switched-in detector element. The average bias current can bechanged in order (i) to compensate for deviations to the entire array ofresistances of the detector elements resulting from changes in ambienttemperatures inside the thermal imaging camera 100 and (ii) tocompensate for array-to-array variations in the average detectorelements of the IR sensor 220. Such bias compensation can beautomatically controlled by the thermal imaging camera 100 or software,or can be user controlled via input to the output/control device 210 orprocessor 222. Following provision of the detector bias and optionalsubtraction or addition of the average bias current, the signals can bepassed through a pre-amp/integrator 226. Typically, thepre-amp/integrator 226 is used to condition incoming signals, e.g.,prior to their digitization. As a result, the incoming signals can beadjusted to a form that enables more effective interpretation of thesignals, and in turn, can lead to more effective resolution of thecreated image. Subsequently, the conditioned signals are sent downstreaminto the processor 222 of the thermal imaging camera 100.

In some embodiments, the front end circuitry 202 can include one or moreadditional elements for example, additional sensors 228 or an ADC 230.Additional sensors 228 can include, for example, temperature sensors,visual light sensors (such as a CCD), pressure sensors, magneticsensors, etc. Such sensors can provide additional calibration anddetection information to enhance the functionality of the thermalimaging camera 100. For example, temperature sensors can provide anambient temperature reading near the IR sensor 220 to assist inradiometry calculations. A magnetic sensor, such as a Hall Effectsensor, can be used in combination with a magnet mounted on the lens toprovide lens focus position information. Such information can be usefulfor calculating distances, or determining a parallax offset for use withvisual light scene data gathered from a visual light sensor.

An ADC 230 can provide the same function and operate in substantiallythe same manner as discussed below, however its inclusion in the frontend circuitry 202 may provide certain benefits, for example,digitization of scene and other sensor information prior to transmittalto the processor 222 via the connection therebetween. In someembodiments, the ADC 230 can be integrated into the ROIC, as discussedabove, thereby eliminating the need for a separately mounted andinstalled ADC 230.

In some embodiments, front end components can further include a shutter240. A shutter 240 can be externally or internally located relative tothe lens and operate to open or close the view provided by the IR lensassembly 104. As is known in the art, the shutter 240 can bemechanically positionable, or can be actuated by an electro-mechanicaldevice such as a DC motor or solenoid. Embodiments of the invention mayinclude a calibration or setup software implemented method or settingwhich utilize the shutter 240 to establish appropriate bias levels foreach detector element.

Components described as processors within thermal imaging camera 100,including processor 222, may be implemented as one or more processors,such as one or more microprocessors, digital signal processors (DSPs),application specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), programmable logic circuitry, or the like, eitheralone or in any suitable combination. Processor 222 may also includememory that stores program instructions and related data that, whenexecuted by processor 222, cause thermal imaging camera 100 andprocessor 222 to perform the functions attributed to them in thisdisclosure. Memory may include any fixed or removable magnetic, optical,or electrical media, such as RAM, ROM, CD-ROM, hard or floppy magneticdisks, EEPROM, or the like. Memory may also include a removable memoryportion that may be used to provide memory updates or increases inmemory capacities. A removable memory may also allow image data to beeasily transferred to another computing device, or to be removed beforethermal imaging camera 100 is used in another application. Processor 222may also be implemented as a System on Chip that integrates some or allcomponents of a computer or other electronic system into a single chip.These elements manipulate the conditioned scene image data deliveredfrom the front end stages 204 in order to provide output scene data thatcan be displayed or stored for use by the user. Subsequently, theprocessor 222 (processing circuitry) sends the processed data to adisplay 108 or other output/control device 210.

During operation of thermal imaging camera 100, processor 222 cancontrol infrared camera module 200 to generate infrared image data forcreating an infrared image. Processor 222 can generate a digital “frame”of infrared image data. By generating a frame of infrared image data,processor 222 captures an infrared image of a target scene atsubstantially a given point in time. That is, in some examples, aplurality of pixels making up the infrared image may be capturedsimultaneously. In other embodiments, sets of one or more pixels may becaptured serially until each pixel has been captured.

Processor 222 can capture a single infrared image or “snap shot” of atarget scene by measuring the electrical signal of each infrared sensorelement included in the FPA of infrared sensor 220 a single time.Alternatively, processor 222 can capture a plurality of infrared imagesof a target scene by repeatedly measuring the electrical signal of eachinfrared sensor element included in the FPA of infrared sensor 220. Inexamples in which processor 222 repeatedly measures the electricalsignal of each infrared sensor element included in the FPA of infraredsensor 220, processor 222 may generate a dynamic thermal image (e.g., avideo representation) of a target scene. For example, processor 222 maymeasure the electrical signal of each infrared sensor element includedin the FPA at a rate sufficient to generate a video representation ofthermal image data such as, e.g., 30 Hz or 60 Hz. Processor 222 mayperform other operations in capturing an infrared image such assequentially actuating a shutter 240 to open and close an aperture ofinfrared lens assembly 104, or the like.

With each sensor element of infrared sensor 220 functioning as a sensorpixel, processor 222 can generate a two-dimensional image or picturerepresentation of the infrared radiation from a target scene bytranslating changes in an electrical characteristic (e.g., resistance)of each sensor element into a time-multiplexed electrical signal thatcan be processed, e.g., for visualization on display 108 and/or storagein memory. When displayed on a display 108, an infrared image cancomprise a plurality of display pixels. Display pixels can have anydefined relationship with corresponding sensor pixels. In some examples,each sensor pixel corresponds to a display pixel in an imagerepresentation of infrared data. In other examples, a plurality ofsensor pixels may be combined (e.g., averaged) to provide infraredinformation for a single display pixel. In still other examples, asingle sensor pixel may contribute to a plurality of display pixels. Forexample, a value from a single sensor pixel may be replicated at nearbypixels, such as in a simple upsampling procedure. In other examples,neighboring or otherwise nearby pixels may be averaged to create a newpixel value, such as in an interpolation procedure. Becauserelationships between display pixels and sensor pixels are defined withrespect to camera operation, the generic term “pixel” may refer to thesensor pixel, the display pixel, or the data as it is processed from thesensor pixel to the display pixel unless otherwise stated. Processor 222may perform computations to convert raw infrared image data into scenetemperatures (radiometry) including, in some examples, colorscorresponding to the scene temperatures.

Processor 222 may control display 108 to display at least a portion ofan infrared image of a captured target scene. In some examples,processor 222 controls display 108 so that the electrical response ofeach sensor element of infrared sensor 220 is associated with a singlepixel on display 108. In other examples, processor 222 may increase ordecrease the resolution of an infrared image so that there are more orfewer pixels displayed on display 108 than there are sensor elements ininfrared sensor 220. Processor 222 may control display 108 to display anentire infrared image (e.g., all portions of a target scene captured bythermal imaging camera 100) or less than an entire infrared image (e.g.,a lesser port of the entire target scene captured by thermal imagingcamera 100). Processor 222 may perform other image processing functions,as described in greater detail below.

Independent of the specific circuitry, thermal imaging camera 100 may beconfigured to manipulate data representative of a target scene so as toprovide an output that can be displayed, stored, transmitted, orotherwise utilized by a user.

Thermal imaging camera 100 includes visible light camera module 206.Visible light camera modules are generally well known. For examples,various visible light camera modules are included in smartphones andnumerous other devices. In some embodiments, visible light camera module206 may be configured to receive visible light energy from a targetscene and to focus the visible light energy on a visible light sensorfor generation of visible light energy data, e.g., that can be displayedin the form of a visible light image on display 108 and/or stored inmemory. Visible light camera module 206 can include any suitablecomponents for performing the functions attributed to the module herein.In the example of FIG. 3, visible light camera module 206 is illustratedas including visible light lens assembly 106 and visible light sensor242. As described above with respect to FIGS. 1 and 2, visible lightlens assembly 106 includes at least one lens that takes visible lightenergy emitted by a target scene and focuses the visible light energy onvisible light sensor 242. Visible light sensor 242 responds to thefocused energy by generating an electrical signal that can be convertedand displayed as a visible light image on display 108. In some examples,the visible light module 206 is configurable by a user, and can provideoutput, for example, to display 108, in a variety of formats. Visiblelight camera module 206 may include compensation functionality forvarying lighting or other operating conditions or user preferences. Thevisible light camera module may provide a digital output including imagedata, which may include data in a variety of formats (e.g., RGB, CYMK,YCbCr, etc.).

Visible light sensor 242 may include a plurality of visible light sensorelements such as, e.g., CMOS detectors, CCD detectors, PIN diodes,avalanche photo diodes, or the like. The number of visible light sensorelements may be the same as or different than the number of infraredlight sensor elements.

In operation, optical energy received from a target scene may passthrough visible light lens assembly 106 and be focused on visible lightsensor 242. When the optical energy impinges upon the visible lightsensor elements of visible light sensor 242, photons within thephotodetectors may be released and converted into a detection current.Processor 222 can process this detection current to form a visible lightimage of the target scene.

During use of thermal imaging camera 100, processor 222 can controlvisible light camera module 206 to generate visible light data from acaptured target scene for creating a visible light image. The visiblelight data may include luminosity data indicative of the color(s)associated with different portions of the captured target scene and/orthe magnitude of light associated with different portions of thecaptured target scene. Processor 222 can generate a “frame” of visiblelight image data by measuring the response of each visible light sensorelement of thermal imaging camera 100 a single time. By generating aframe of visible light data, processor 222 captures visible light imageof a target scene at a given point in time. Processor 222 may alsorepeatedly measure the response of each visible light sensor element ofthermal imaging camera 100 so as to generate a dynamic thermal image(e.g., a video representation) of a target scene, as described abovewith respect to infrared camera module 200. In some examples, thevisible light camera module 206 may include its own dedicated processoror other circuitry (e.g., ASIC) capable of operating the visible lightcamera module 206. In some such embodiments, the dedicated processor isin communication with processor 222 for providing visible light imagedata (e.g., RGB image data) to processor 222. In alternativeembodiments, a dedicated processor for the visible light camera module206 may be integrated into processor 222.

With each sensor element of visible light camera module 206 functioningas a sensor pixel, processor 222 can generate a two-dimensional image orpicture representation of the visible light from a target scene bytranslating an electrical response of each sensor element into atime-multiplexed electrical signal that can be processed, e.g., forvisualization on display 108 and/or storage in memory.

Processor 222 may control display 108 to display at least a portion of avisible light image of a captured target scene. In some examples,processor 222 controls display 108 so that the electrical response ofeach sensor element of visible light camera module 206 is associatedwith a single pixel on display 108. In other examples, processor 222 mayincrease or decrease the resolution of a visible light image so thatthere are more or fewer pixels displayed on display 108 than there aresensor elements in visible light camera module 206. Processor 222 maycontrol display 108 to display an entire visible light image (e.g., allportions of a target scene captured by thermal imaging camera 100) orless than an entire visible light image (e.g., a lesser port of theentire target scene captured by thermal imaging camera 100).

In some embodiments, one or both of infrared 200 and visible light 206camera modules for acquiring IR and VL image data may be included in animage acquisition module 280. The image acquisition module may be inwired or wireless communication with a processing module 290 thatincludes a processor such as 222. Processing module 290 may receiveimage data from the image acquisition module 280 and perform subsequentprocessing steps as will be described herein. In some examples,processing module 290 may include portable processing devices, such as asmartphone, a tablet, a stand-alone computer such as a laptop or desktopPC, or the like. In some such embodiments, various components of frontend circuitry 202 may be included in the image acquisition module 280,the processing module 290, or both.

In these and other examples, processor 222 may control display 108 toconcurrently display at least a portion of the visible light imagecaptured by thermal imaging camera 100 and at least a portion of theinfrared image captured by thermal imaging camera 100. Such a concurrentdisplay may be useful in that an operator may reference the featuresdisplayed in the visible light image to help understand the featuresconcurrently displayed in the infrared image, as the operator may moreeasily recognize and distinguish different real-world features in thevisible light image than the infrared image. In various examples,processor 222 may control display 108 to display the visible light imageand the infrared image in side-by-side arrangement, in apicture-in-picture arrangement, where one of the images surrounds theother of the images, or any other suitable arrangement where the visiblelight and the infrared image are concurrently displayed.

For example, processor 222 may control display 108 to display thevisible light image and the infrared image in a combined arrangement. Insuch an arrangement, for a pixel or set of pixels in the visible lightimage representative of a portion of the target scene, there exists acorresponding pixel or set of pixels in the infrared image,representative of substantially the same portion of the target scene. Invarious embodiments, the size and/or resolution of the IR and VL imagesneed not be the same. Accordingly, there may exist a set of pixels inone of the IR or VL images that correspond to a single pixel in theother of the IR or VL image, or a set of pixels of a different size.Similarly, there may exist a pixel in one of the VL or IR images thatcorresponds to a set of pixels in the other image. Thus, as used herein,corresponding does not require a one-to-one pixel relationship, but mayinclude mismatched sizes of pixels or groups of pixels. Variouscombination techniques of mismatched sized regions of images may beperformed, such as up- or down-sampling one of the images, or combininga pixel with the average value of a corresponding set of pixels. Otherexamples are known and are within the scope of this disclosure.

Thus, corresponding pixels need not have a direct one-to-onerelationship. Rather, in some embodiments, a single infrared pixel has aplurality of corresponding visible light pixels, or a visible lightpixel has a plurality of corresponding infrared pixels. Additionally oralternatively, in some embodiments, not all visible light pixels havecorresponding infrared pixels, or vice versa. Such embodiments may beindicative of, for example, a picture-in-picture type display aspreviously discussed. Thus, a visible light pixel will not necessarilyhave the same pixel coordinate within the visible light image as does acorresponding infrared pixel. Accordingly, as used herein, correspondingpixels generally refers pixels from any image (e.g., a visible lightimage, an infrared image, a combined image, a display image, etc.)comprising information from substantially the same portion of the targetscene. Such pixels need not have a one-to-one relationship betweenimages and need not have similar coordinate positions within theirrespective images.

Similarly, images having corresponding pixels (i.e., pixelsrepresentative of the same portion of the target scene) can be referredto as corresponding images. Thus, in some such arrangements, thecorresponding visible light image and the infrared image may besuperimposed on top of one another, at corresponding pixels. An operatormay interact with user interface 208 to control the transparency oropaqueness of one or both of the images displayed on display 108. Forexample, the operator may interact with user interface 208 to adjust theinfrared image between being completely transparent and completelyopaque and also adjust the visible light image between being completelytransparent and completely opaque. Such an exemplary combinedarrangement, which may be referred to as an alpha-blended arrangement,may allow an operator to adjust display 108 to display an infrared-onlyimage, a visible light-only image, of any overlapping combination of thetwo images between the extremes of an infrared-only image and a visiblelight-only image. Processor 222 may also combine scene information withother data, such as radiometric data, alarm data, and the like. Ingeneral, an alpha-blended combination of visible light and infraredimages can comprise anywhere from 100 percent infrared and 0 percentvisible light to 0 percent infrared and 100 percent visible light. Insome embodiments, the amount of blending can be adjusted by a user ofthe camera. Thus, in some embodiments, a blended image can be adjustedbetween 100 percent visible light and 100 percent infrared.

Additionally, in some embodiments, the processor 222 can interpret andexecute commands from user interface 208, and/or output/control device210. This can involve processing of various input signals andtransferring those signals to the front end circuitry 202 via aconnection therebetween. Components (e.g. motors, or solenoids)proximate the front end circuitry 202 can be actuated to accomplish thedesired control function. Exemplary control functions can includeadjusting the focus, opening/closing a shutter, triggering sensorreadings, adjusting bias values, etc. Moreover, input signals may beused to alter the processing of the image data that occurs in theprocessor 222.

Processor can further include other components to assist with theprocessing and control of the infrared imaging camera 100. For example,as discussed above, in some embodiments, an ADC can be incorporated intothe processor 222. In such a case, analog signals conditioned by thefront-end stages 204 are not digitized until reaching the processor 222.Moreover, some embodiments can include additional on board memory forstorage of processing command information and scene data, prior totransmission to the display 108 or the output/control device 210.

An operator may interact with thermal imaging camera 100 via userinterface 208, which may include buttons, keys, or another mechanism forreceiving input from a user. The operator may receive output fromthermal imaging camera 100 via display 108. Display 108 may beconfigured to display an infrared-image and/or a visible light image inany acceptable palette, or color scheme, and the palette may vary, e.g.,in response to user control. In some examples, display 108 is configuredto display an infrared image in a monochromatic palette such asgrayscale. In other examples, display 108 is configured to display aninfrared image in a color palette such as, e.g., amber, ironbow,blue-red, or other high contrast color scheme. Combinations of grayscaleand color palette displays are also contemplated. In some examples, thedisplay being configured to display such information may includeprocessing capabilities for generating and presenting such image data.In other examples, being configured to display such information mayinclude the ability to receive image data from other components, such asprocessor 222. For example, processor 222 may generate values (e.g., RGBvalues, grayscale values, or other display options) for each pixel to bedisplayed. Display 108 may receive such information and map each pixelinto a visual display.

While processor 222 can control display 108 to concurrently display atleast a portion of an infrared image and at least a portion of a visiblelight image in any suitable arrangement, a picture-in-picturearrangement may help an operator to easily focus and/or interpret athermal image by displaying a corresponding visible image of the samescene in adjacent alignment.

A power supply (not shown) delivers operating power to the variouscomponents of thermal imaging camera 100 and, in some examples, mayinclude a rechargeable or non-rechargeable battery and a powergeneration circuit.

During operation of thermal imaging camera 100, processor 222 controlsinfrared camera module 200 and visible light camera module 206 with theaid of instructions associated with program information that is storedin memory to generate a visible light image and an infrared image of atarget scene. Processor 222 further controls display 108 to display thevisible light image and/or the infrared image generated by thermalimaging camera 100.

FIG. 4 is a front view of a thermal imaging camera such as that shown inFIG. 1. As shown, the thermal imaging camera 400 includes a housing 402,and infrared lens assembly 404, a visible light lens assembly 406, alaser 410, and a focus ring 414. In the illustrated embodiment, each ofthe infrared lens assembly 404, the visible light lens assembly 406, andthe laser 410 are located within the perimeter of the focus ring 414.

Such a configuration allows for the visible light lens assembly 406 andthe infrared lens assembly 404 to be positioned closer together than ifthe visible light lens assembly 406 were positioned outside theperimeter of the focus ring 414 while the infrared lens assembly 404 ispositioned within the perimeter. Similarly, the laser 410 can bepositioned more closely to the infrared lens assembly 404 than if itwere located outside of the perimeter of the focus ring. In addition,positioning both the laser 410 and the visible light lens assembly 406inside the perimeter of the focus ring 414 can position such elementscloser together than if just one of such elements were positioned insidethe perimeter of the focus ring 414. This positioning can reduceparallax errors between the infrared lens assembly 404 and the visiblelight lens assembly 406, between the infrared lens assembly 404 and thelaser 410, and/or between the visible light lens assembly 406 and thelaser 410. In some exemplary embodiments, the separation between theoptical axes of the visible light lens assembly 406 and the infraredlens assembly 404 is approximately 0.8 inches. In some embodiments, theclosely placed infrared lens assembly 404 and visible light lensassembly 406 can significantly reduce parallax errors when compared toembodiments in which the visible light lens assembly 406 and theinfrared lens assembly 404 are spaced further away.

In some embodiments, the infrared lens assembly 404 sized with respectto the diameter of the focus ring 414 so that other components may alsofit within the perimeter of the focus ring 414. For instance, in anexemplary embodiment, the focus ring 414 is sized to ergonomically fit atypical user. That is, the outer diameter of the focus ring 414 can beselected for optimum comfort and maneuverability of a user. In someexamples, the outer diameter of the focus ring 414 can additionally oralternatively be made relative to the size of other components (e.g.,display 108) of the camera. For instance, in an exemplary embodiment,the display (e.g., 108) is approximately 3.5 inches diagonal, and thefocus ring 414 is about 2.7 inches in diameter so that the user iscomfortable operating the focus ring 414 relative to the overall camerasize.

In the illustrated embodiment, the optical axis of the infrared lensassembly 404 is offset from the centerline of the focus ring 414. Incombination with the relative size of the infrared lens assembly 404compared to the perimeter of the focus ring 414, positioning theinfrared lens assembly 404 offset from the center of the focus ring 414frees up more usable space within the perimeter of the ring 414,allowing the visible light lens assembly 406, as well as the laser, tobe positioned therein. While not shown in the illustrated embodiment,some thermal imaging cameras can include a torch configured toilluminate the target scene by emitting light toward the scene. In somesuch examples, the torch may similarly be positioned within theperimeter of the focus ring 414. This can prevent components of thecamera from casting shadows on the target scene by partially blockinglight emitted from the torch.

The thermal imaging camera 400 of FIG. 4 includes a faceplate 440disposed in the perimeter of the focus ring 414 to protect interiorcomponents of the camera 400. FIG. 5 is a front view of a thermalimaging camera such as that of FIG. 4 with the faceplate removed. In theillustrated embodiment, the infrared lens assembly 504 is surrounded byan inner gear 524. The inner gear 524 can be configured to engage theinfrared lens assembly 504 so that rotation of the inner gear 524 causessimilar rotation of the infrared lens assembly. 504. As shown, the focusring 514 of the thermal imaging camera 500 functions as a ring gearhaving teeth 520 that engage teeth 530 of the inner gear 524. In such aconfiguration, when the focus ring 514 is rotated, the teeth 520 of thering gear engage the teeth 530 of the inner gear 524, causing the innergear to similarly rotate. However, it will be noted that, while the ringgear of the focus ring 514 and the inner gear 524 are configured torotate together, they do not rotate about the same axis. Rather, theaxis of rotation of the inner gear 524 is offset from the axis ofrotation of the focus ring 514. In the illustrated example, the axis ofrotation of the inner gear 524 is approximately the same as the opticalaxis of the infrared lens assembly 504. If the inner gear 524 is engagedwith the infrared lens assembly 504, rotation of the inner gear 524likewise causes rotation of the infrared lens assembly 504 about itsoptical axis. While shown in the illustrated embodiment as engaging oneanother by meshing teeth 520, 530, it will be appreciated that theengaging relationship between the focus ring 514 and the inner gear 524can include a number of possibilities. For instance, in someembodiments, one or both of the inner surface of the focus ring 514 andthe outer surface of the inner gear 524 can include a high-frictionsurface such that the friction between the two components causesrotation of the inner gear 524 when the focus ring 514 is rotated.

In some examples, focus ring 514 (and thus, in some examples, the innergear 524 and infrared lens assembly 504) rotates relative to the housing502 of the thermal imaging camera. In some embodiments, the focus ring514 rotates relative to the housing 502 while components located insidethe perimeter of the focus ring 514 such as the visible light lensassembly 506 and the laser 510 remain stationary relative to the housing502. That is, in some embodiments, rotation of the focus ring 514 causesrotation of the inner gear 524 and the infrared lens assembly 504, butthe visible light lens assembly 506 and the laser 510 remain stationary.

FIG. 6 is an exploded view of portions of an exemplary thermal imagingcamera according to some embodiments. In the illustrated embodiment, theinfrared lens assembly 604, the visible light lens assembly 606, and thelaser 610 are each supported by a structure referred to as the sensorcan 660. In some examples, the sensor can 660 can be formed from asingle piece of material, such as a machined metal or a molded metal orplastic. While shown as being supported by the sensor can 660, theinfrared lens assembly 604, the visible light lens assembly 606, and/orthe laser 610 need not be fixedly attached to the sensor can 660. Forexample, in some embodiments, the infrared lens assembly 604 is capableof axial rotation within the sensor can 660.

The thermal imaging camera 600 includes a focus ring 614 interfacingwith an inner gear 624. As described elsewhere herein, rotation of thefocus ring 614 can cause rotation of the inner gear 624, for example, byway of meshing teeth at the interface between the components. In theillustrated embodiment, the sensor can 660 is aligned so that infraredlens assembly 604 is aligned with the inner gear 624 within theperimeter of the focus ring 614 as well as an infrared lens aperture 644in the faceplate 640. As shown, such components are aligned alonginfrared optical axis 684. Accordingly, when assembled, a portion of theinfrared lens assembly 604 protrudes through the housing 602 andinterfaces with the inner gear 624. The faceplate 640 can be attached sothat it blocks minimal or no infrared radiation from impinging on theinfrared lens assembly 604.

The faceplate 640 can include visible light aperture 646 and laseraperture 650 for permitting light to be detected or emitted by thevisible light lens assembly 606 and the laser 610 along axes 686 and690, respectively. As shown, visible light optical axis 686 and laseraxis 690 each extend through a gap within the perimeter of the focusring 614. Thus, rotation of the focus ring 614 and the inner gear 624happens independently from and does not interfere with the visible lightlens assembly 606 and the laser 610.

Various portions of the thermal imaging camera can include interfacingcomponents configured to facilitate engagement between components and/orlimit the motion of components. For instance, in some embodiments, thehousing 602 includes stops 603 which may limit the rotation of the focusring 614 about the housing 602, which may in turn limit the rotation ofthe inner gear 624 and the infrared lens assembly 604. Additionally oralternatively, the infrared lens assembly 604 can include an engagementportion such as groove 605 for engaging a portion of the inner gear 624.

During exemplary operation of the illustrated embodiment, whenassembled, the focus ring 614 is rotatable relative to the housing 602,sensor can 660, and the faceplate 640, each of which remain may remainstationary while the focus ring 614 rotates. The focus ring 614 includesa ring gear which engages an inner gear 624, which engages the infraredlens assembly 604 via the groove 605 therein. Rotation of the focus ring614 causes rotation of the inner gear 624, which causes rotation of theinfrared lens assembly 604 within the sensor can 660. In some examples,the amount of rotation of the focus ring 614 is limited by stops 603 onthe housing 602.

In some examples, thermal imaging camera 600 can be assembled via amethod illustrated by FIG. 6. In an exemplary assembly method, aninfrared lens assembly 604 can be threadably engaged with a sensor can660. The infrared lens assembly 604 and sensor can 660 can be insertedinto a back side of a housing 602. An inner gear 624 can engage theinfrared lens assembly 604 from a front side of the housing 602, thefront side being opposite the back side of the housing. The inner gear624 can be attached to the infrared lens assembly 604 such that rotationof the inner gear 624 causes rotation of the infrared lens assembly 604,for example, by way of the groove 605 on the infrared lens assembly 604and a corresponding tab on the inner gear. Additionally oralternatively, assembly methods can include the steps of positioning avisible light lens assembly 606, a laser 610, a torch (not shown),and/or other component within the sensor can.

According to some exemplary assembly methods, the focus ring 614 can beadded to the front side of the housing 602 so that an inner surface ofthe focus ring 614 engages an outer surface of the inner gear 624. Insome such examples, rotation of the focus ring 614 causes rotation ofthe inner gear 624. Thus, in some embodiments, components are assembledsuch that rotating the focus ring 614 causes rotation of the inner gear624, which causes rotation of the infrared lens assembly 604 within thesensor can 660.

FIG. 7 is a back view of an exemplary focus ring and inner gear. In theillustrated example, the focus ring 714 includes an inner surface havinga plurality of teeth 720 configured to engage and mesh with teeth 730 onan outer surface of the inner gear 724. As described elsewhere herein,the engagement between teeth 730 of the inner gear 724 and the teeth 720of the focus ring 714 can result in the inner gear 724 rotating wheneverthe focus ring 714 is rotated.

In the exemplary embodiment of FIG. 7, the focus ring 714 includes agrip surface 715 (shaded) to facilitate the grasping and rotating by auser. The grip surface 715 can provide a comfortable surface for theuser to grip as well as sufficient friction (e.g., via one or both oftexture and material) to eliminate excessive slipping of a user's handon the focus ring 714. The exemplary focus ring 714 of FIG. 7 furtherincludes stops 713 (shaded) disposed on the back surface thereof. Stops713 can be configured to engage with a portion of the thermal imagingcamera (e.g., stops 603 on the housing 602 in FIG. 6) in order to limitthe rotation of the focus ring 714. In a particular example, stops 713of the focus ring 714 and corresponding stops (e.g., 603) on the thermalimaging camera can limit rotation of the focus ring 714 to a range ofapproximately 210°.

In some examples the camera can be assembled in a pre-selected initialfocus position. For example, with reference to FIG. 6, in someembodiments, the housing 602 and the focus ring 614 include assemblyalignment marks (633, 634, respectively) such that aligning the marks633, 634 during assembly results in the pre-selected initial focusposition. In some exemplary assembly methods, the infrared lens assembly(e.g., 604) can be threaded to a known focus position in the sensor can(e.g., 660) so that the infrared lens assembly can be rotated in eitherdirection about its optical axis (e.g., 684) within the sensor can andremain threadably engaged therewith. Similarly, the focus ring can bepositioned on the front side of the housing using assembly alignmentmarks 633, 634 such that the focus ring can be rotated in eitherdirection about its central axis without being immediately limited bystops (e.g., 603, 713). For instance, in an exemplary configuration, thefocus ring can be positioned on the housing such that the focus ring canbe rotated substantially the same amount in either direction before oneof stops 713 encounters one of stops 603 and prevents further rotationthe focus ring. In other examples, the position of the focus ring 614,when aligned with the housing 602 via the assembly alignment marks 633,634, is not centered between stops 603, but rather is offset onedirection or another. For instance, in an alternative embodiment, theinfrared lens assembly can be threaded to an extreme (i.e., a maximum orminimum) focal position and the focus ring can be installed so that astop 713 is immediately adjacent to a corresponding stop 603 to preventadditional rotation past the extreme focal position. Such assemblyprocesses can place the camera in a focus position wherein rotating thefocus ring 614 as permitted by the stops 603, 713 safely rotates theinfrared lens assembly 604 within the sensor can 660 without risk of theinfrared lens assembly 604 rotating too far within the sensor can 660.Otherwise, excess rotation of the infrared lens assembly can cause theinfrared lens assembly to unscrew from and disengage the sensor canand/or cause the threads to bind and become damaged.

In the embodiment of FIG. 7, the inner gear 724 includes a tab 725 thatcan interface with a corresponding portion of the infrared lensassembly. For example, tab 725 can interface with a groove (e.g., 605 ofFIG. 6) of the infrared lens assembly (e.g., 604 of FIG. 6). Suchengagement can couple the inner gear 724 and the infrared lens assemblysuch that rotation of the inner gear 724 causes rotation of the infraredlens assembly.

FIG. 8 is an exploded view showing an exemplary configuration between aninner gear and an infrared lens assembly. In the illustrated example, aninner gear 824 includes an aperture and a tab 825 projecting inwardtoward the aperture. In the illustrated example, the infrared lensassembly 804 is supported by a sensor can 860 and includes a groove 805formed in an outer edge thereof. As shown by the broken-line arrow, thetab 825 in the inner gear 824 aligns with groove 805 in the infraredlens assembly 804 such that the groove 805 may receive the tab 825.

In the illustrated embodiment, the aperture in the inner gear 824 isconfigured such that a portion of the infrared lens assembly 804protrudes into the aperture of the inner gear 824 when the groove 805receives the tab 825. Because the tab 825 of the inner gear is receivedby the groove 805 of the infrared lens assembly 804, rotation of theinner gear 824 about the optical axis of the infrared lens assembly 804causes rotation of the infrared lens assembly 804 about its opticalaxis. As described elsewhere herein, in some embodiments, the infraredlens assembly 804 is rotatable within the sensor can 860. Accordingly,rotation of the inner gear 824 can cause rotation of the infrared lensassembly 804 within the sensor can 860 while the sensor can 860 remainsstationary. In some embodiments, the inner gear 824 may be integrallyformed with a portion of the infrared lens assembly such that both theinner gear 824 and the infrared lens assembly rotate together as onepiece.

FIG. 9 is a cross-sectional view of portions of an exemplary thermalimaging camera taken along line 9-9 in FIG. 5. In the illustratedexample, the thermal imaging camera includes an infrared lens assembly904. The infrared lens assembly 904 of FIG. 9 includes a frame (shadedin light gray) supporting two lenses 950 and 952. It will be appreciatedthat a single lens or other number of lenses can be included in theinfrared lens assembly 904.

The thermal imaging camera of FIG. 9 includes a focus ring 914 thatengages an inner gear 924, for example, via intermeshing teeth such asshown in the examples of FIGS. 5-7. In some embodiments, inner gear 924comprises an interfacing portion for engaging a portion of infrared lensassembly 904 to secure the infrared lens assembly 904 to the inner gear924. For example, in some embodiments, the interfacing portion comprisesa tab (e.g., 825 in FIG. 8) for engaging a groove (e.g., 805 in FIG. 8)in the infrared lens assembly 904 (e.g., in the frame). As describedelsewhere herein, in some examples, engagement between the focus ring914 and the inner gear 924 in combination with engagement between theinner gear 924 and the infrared lens assembly 904 can operate so that,when the focus ring 914 is rotated about its center axis (994), theinfrared lens assembly 904 also rotates about its center axis (984). Inthe embodiment of FIG. 9, the axis of rotation (994) of the focus ring914 is offset from the axis of rotation (984) of the infrared lensassembly 904. In some examples, the inner gear 924 rotates about thesame axis as the infrared lens assembly (e.g., 984).

As shown, the infrared lens assembly 904 is generally supported bysensor can 960 (shaded dark gray). As described elsewhere herein, sensorcan 960 can support additional components, such as a visible light lensassembly, a laser, or other components of the thermal imaging camera. Insome examples, the sensor can 960 is fixed relative to an infraredsensor 920 of the camera. In the illustrated embodiment, the infraredlens assembly 904 includes threads 907 interfacing with threads 967 ofthe sensor can 960. Accordingly, in some such embodiments, rotation ofthe infrared lens assembly 904 with respect to the sensor can 960 cancause the infrared lens assembly 904 to also translate with respect tothe sensor can 960.

During a focusing operation of an exemplary embodiment of a thermalimaging camera, a user may grasp and rotate the focus ring 914. Therotation of the focus ring 914 causes rotation of the inner gear 924,for example, via intermeshing teeth of an inner surface of the focusring 914 and an outer surface of the inner gear 924. Rotation of theinner gear 924 in turn causes rotation of the infrared lens assembly904, which rotates about its center axis 984 and relative to the sensorcan 960. The threaded engagement between the infrared lens assembly 904and the sensor can 960 causes the infrared lens assembly 904 totranslate with respect to the sensor can 960 along its axis of rotation984 upon rotation. If the sensor can 960 is fixed relative to the IRsensor 920, translation of the infrared lens assembly 904 relative tothe sensor can 960 similarly results in translation of the infrared lensassembly 904 relative to the IR sensor 920, which in some embodiments,is located substantially along the axis of rotation 984 of the infraredlens assembly 904. Thus, the infrared lens assembly 904 translatestoward or away from the infrared sensor, thereby adjusting the infraredimaging focal distance.

As described elsewhere herein, in some examples, portions of the thermalimaging camera can include stops (e.g., 603 on the housing 602 in FIG.6; 713 on the focus ring 714 in FIG. 7) that can limit the rotation ofthe focus ring 714. In some embodiments, stops may be positioned so asto limit the rotation or translation of additional or alternativecomponents. Accordingly, in some embodiments, limits are placed on themotion of one or more components, which may ultimately limit the traveldistance of the infrared lens assembly 904 within the sensor can 960.This may prevent the infrared lens assembly 904 from “unscrewing” fromthe sensor can 960 and/or excessive travel of the infrared lens assembly904, which may otherwise collide with other components within thethermal imaging camera. In some embodiments, maximum travel distance bythe infrared lens assembly 904 is approximately 0.02 inches.

In some embodiments, a small travel distance between focal extremes ofthe infrared lens assembly 904 requires precise movement and alignmentof the infrared lens assembly 904 relative to other components, such asan infrared sensor 920. In some embodiments, the thermal imaging cameraincludes components for stabilizing the infrared lens assembly in placewithin the camera. For instance, in the illustrated embodiment of FIG.9, the camera includes a wave spring 964 positioned between a portion ofthe infrared lens assembly 904 and the sensor can 960 to press theinfrared lens assembly 904 against the sensor can 960. This can serve toreduce misalignment such as tilting or wobbling of the infrared lensassembly 904, for example, in the threads 907. Other springs orcomponents capable of increasing the force between the infrared lensassembly 904 and the sensor can 960 can be used alternatively or inaddition to wave spring 964. Different spring configurations can providedifferent numbers of points of pressure exerted on the infrared lensassembly 904 and the sensor can 960. In some embodiments, wave spring964 can contact each of the infrared lens assembly 904 and the sensorcan 960 in three or more points around a circumference. Three or moreindividual spring components can similarly provide three or more pointsof contact between the infrared lens assembly 904 and the sensor can960. In some embodiments, an elastic material may provide continuouscontact to the infrared lens assembly 904 and the sensor can 960 aboutan entire circumference.

In some embodiments, the camera is capable of determining the currentfocal position of the infrared lens assembly 904. In the illustratedembodiment, the camera includes a plunger 970 operably engaging theinfrared lens assembly 904. In some examples, plunger 970 can be pressedagainst the infrared lens assembly 904 via a spring 972. Additionally oralternatively, spring 972 can provide added resistance to movement ofthe infrared lens assembly 904 toward the camera body. During exemplaryoperation, if the infrared lens assembly 904 is moved proximally towardthe camera body (to the left in the example of FIG. 9), the spring 972is compressed and the plunger 970 moves proximally.

The camera can include a sensor 974 configured to measure the proximityof the plunger 970. In some examples, the sensor 974 is fixed relativeto the sensor can 960 so that motion of the infrared lens assembly 904within the sensor can 960 causes the plunger 970 to similarly moverelative to the sensor 974. Thus, in some embodiments, the sensor 974can output a signal indicative of the distance between the plunger 970and the sensor 974, which can be received by a processor (e.g., 222 fromFIG. 3). The distance between the plunger 970 and the sensor 974 can beconverted into a relative position of the infrared lens assembly 904relative to an infrared imaging element 920, and thus a relative orabsolute focal distance of the camera. For example, in some embodiments,the infrared sensor 920 and sensor 974 can be fixed to a sensor board975 that is maintained stationary relative to the sensor can 960.Rotating the focus ring 914 can cause movement of the infrared lensassembly 904 and the plunger 970 relative to the sensor board 975.

In some exemplary embodiments, the plunger 970 can include a magnetdetectable by a sensor 974 such as a magnetic encoder. In various suchexamples, the plunger 970 can comprise a magnetic material or cansupport a magnet, for example, mounted on or in its proximal end 971.The sensor 974 can include an encoder capable of measuring the fieldstrength of the magnetic field present at the sensor 974 from the magnetof the plunger 970. Other proximity detecting technologies are possiblefor use in determining a distance traveled by and/or an absoluteposition of the plunger 970 in order to establish an absolute orrelative focal position of the infrared lens assembly 904.

Various embodiments have been described. Such examples are non-limiting,and do not define or limit the scope of the invention in any way.Rather, these and other examples are within the scope of the followingclaims.

1. An adjustable-focus thermal imaging camera comprising an infraredsensor configured to receive infrared radiation from a target scene andgenerate infrared image data of the target scene; an infrared lensassembly comprising at least one lens defining an optical axis, theinfrared lens assembly being configured to focus infrared radiation ontothe infrared sensor; an inner gear engaging and substantiallysurrounding a portion of the infrared lens assembly; a focus ringsubstantially surrounding the inner gear and the infrared lens assemblyand having an inner surface that engages an outer surface of the innergear; wherein when the focus ring is rotated, the engagement between theinner surface of the focus ring and the outer surface of the inner gearcauses the infrared lens assembly to rotate about its optical axis. 2.The thermal imaging camera of claim 1, further comprising: a visiblelight sensor configured to receive visible light radiation from a targetscene and generate visible light image data representative of the targetscene; and a visible light lens assembly comprising at least one lensand configured to focus visible light radiation onto the visible lightsensor; and wherein the focus ring defines a perimeter such that theinfrared lens assembly and the visible light lens assembly are bothwithin the perimeter defined by the focus ring.
 3. The thermal imagingcamera of claim 2, further comprising a laser configured to emit lighttoward the target scene, and wherein the laser is located within theperimeter defined by the focus ring.
 4. The thermal imaging camera ofclaim 3, further comprising a sensor can, the sensor can configured tosupport the visible light lens assembly, the laser, and the infraredlens assembly.
 5. The thermal imaging camera of claim 4, wherein theinfrared lens assembly is threadably engaged with the sensor can suchthat rotation of the infrared lens assembly causes the infrared lensassembly to translate with respect to the sensor can.
 6. The thermalimaging camera of claim 5, further comprising a spring engaging at leastone of the infrared lens assembly and the sensor can and configured toincrease the pressure between the threadably engaged portions of theinfrared lens assembly and the sensor can.
 7. The thermal imaging cameraof claim 6, wherein the spring comprises a wave spring extendingcircumferentially around a portion of the infrared lens assembly.
 8. Thethermal imaging camera of claim 5, wherein the infrared sensor is fixedrelative to the sensor can, such that translation of the infrared lensassembly relative to the sensor can causes translation of the infraredlens assembly relative to the infrared sensor.
 9. The thermal imagingcamera of claim 8, further comprising a sensor configured to determinethe focal position of the infrared lens assembly relative to theinfrared sensor.
 10. The thermal imaging camera of claim 9, wherein thesensor comprises a detector fixed relative to the infrared sensor and aplunger adapted to move as the infrared lens assembly moves, thedetector being capable of sensing the relative distance to the plungerand relative movement of the plunger toward and away from the detector.11. The thermal imaging camera of claim 1, wherein the outer surface ofthe inner gear and the inner surface of the focus ring each comprise aplurality of teeth, and wherein the teeth of the inner gear engage withthe teeth of the focus ring so that rotation of the focus ring causesrotation of the inner gear.
 12. The thermal imaging camera of claim 1,wherein the inner gear and the infrared lens assembly are integrallyassembled to eliminate relative motion between the parts.
 13. Thethermal imaging camera of claim 1, wherein the focus ring comprises oneor more stops formed therein and the infrared camera comprises one ormore corresponding stops configured to limit rotation of the focus ring.14. The thermal imaging camera of claim 13, further comprising a housingconfigured to house the infrared lens assembly and wherein the one ormore corresponding stops are formed in the housing.
 15. The thermalimaging camera of claim 1, further comprising a sensor configured todetermine the focal position of the infrared lens assembly relative tothe infrared sensor.
 16. An adjustable-focus thermal imaging cameracomprising an infrared sensor configured to receive infrared radiationfrom a target scene and generate infrared image data of the targetscene; an infrared lens assembly comprising at least one lens definingan optical axis, the infrared lens assembly being configured to focusinfrared radiation onto the infrared sensor; a focus ring substantiallysurrounding the infrared lens assembly and having a central axis, thefocus ring configured such that rotation of the focus ring about itscentral axis causes the infrared lens assembly to move relative to theinfrared sensor and wherein the central axis of the focus ring is offsetfrom the optical axis of the at least one lens in the infrared lensassembly.
 17. The thermal imaging camera of claim 16, further comprisinga visible light sensor configured to receive visible light radiationfrom a target scene and generate visible light image data representativeof the target scene; a visible light lens assembly configured to focusvisible light radiation onto a visible light sensor; and a sensor can,the sensor can configured to support the visible light lens assembly andthe infrared lens assembly; and wherein the focus ring defines aperimeter such that the infrared lens assembly and the visible lightlens assembly are both within the perimeter defined by the focus ring.18. The thermal imaging camera of claim 17, further comprising an innergear engaging a portion of the infrared lens assembly and a portion ofthe focus ring such that, when the focus ring is rotated, the inner gearcauses the infrared lens assembly to rotate within the sensor can. 19.The thermal imaging camera of claim 18, wherein the infrared lensassembly is threadably engaged with the sensor can such that rotation ofthe inner gear within the sensor can causes the infrared lens assemblyto translate relative to the sensor can.
 20. The thermal imaging cameraof claim 17, further comprising a spring disposed between a surface ofthe infrared lens assembly and the sensor can and configured to contactthe infrared lens assembly and the sensor can in at least threelocations to press the infrared lens assembly against a portion of thesensor can in substantially the same direction as the optical axisdefined by the at least one lens in the infrared lens assembly.